Compton scattering from the proton

The proton Compton effect has been studied in the region between the threshold for pion photoproduction and the {Δ}(1232). The measurements were performed using bremmstrahlung from the high duty-factor electron beam available at the Saskatchewan Accelerator Laboratory. Elastically scattered photons were detected with an energy resolution of approximately 1.5% using a large NaI total absorption scintillation detector. Differential cross sections were measured for photon energies in the range 136 MeV{≤}E_γ{≤}289 MeV and for angles in the range 25^∘{}θlab135^∘{}. The angular distributions and the excitation functions derived from these data are in agreement with recent theoretical analyses. The results were interpreted within a formalism based in part on dispersion relations to obtain model-dependent estimates of the electric and magnetic polarizabilities, {α}{} and {β}{}. We find, subject to the dispersion sum rule constraint {α}{}+{β}{}=(14.2±{}0.5)×{}10^-4 fm³, that {α}{}=(9.8±{}0.4±{}1.1)×{}10^-4 fm³ and {β}{}=(4.4{∓}0.4{∓}1.1)×{}10^-4 fm³, which are consistent with the best previous measurements.